If you don't have health insurance, you should try to get some!
Health insurance is good for the whole family. It's not just in case of serious injury. It also pays for services like screenings and check-ups that can prevent you from getting sick. If your child has developmental issues, you might need more of these visits.
If your child does have a developmental disability (which includes autism), they might qualify for MassHealth (Medicaid). This is a state-run program that has good benefits for people with disabilities.
Many private health insurers cover ABA therapy and other autism services.